Pump for liquid fuel supply systems



Dec. 25, 1934. w. c. CARTER PUMP FOR LIQUID FUEL SUPPLY SYSTEMS Filed Feb. 25, 1928 2 Sheets-Sheet 1 a IL t HUM-NHL;

Dec. 25, 1934. w. c. CARTER PUMP FOR LIQUID FUE L SUPPLY SYSTEMS 2 Sheets-Sheet 2 Filed Feb. 25, 1928 Hw- TORNEYQ mama p e. 25, me

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This invention relates to pumps of the kind that are used in fuel supply systems for internal combustion engines, for drawing liquid fuel from a source of supply and delivering it to the carburetor of the engine.

One object of my present invention is to provide a fuel pump of novel construction, that is compact, inexpensive to manufacture and reliable in operation.

Figure 1 of the drawings is a vertical sectional view of a pump embodying my present invention, said view being taken on the line 1--1 of Figure 2.

Figure 2 is a vertical sectional view, taken on her of the carburetor of the fuel supply system of which the pump forms a part.

Figure 3 is an enlarged sectional view of the discharge valve of the pump. Figure 4 is a fragmentary sectional view of the diaphragm of the pump, illustrating the means that is used to prevent the diaphragm from being subjected to strains or pressures tending to disrupt it, showing the diaphragm at the end of its suction stroke.

Figure5 is a similar view, showing the dia: phragm at the end of its discharge stroke; and

Figure 6 is a side elevational view, illustrating a fuel supply system embodying my invention. 30 Referring to Figure 6 of the drawings, which illustrates a fuel supply system embodying my invention, A designates an internal combustion engine, B designates the carburetor of the engine, C designates the float chamber of the carburet'or, D designates a tank that holds a supply of liquid fuel, E designates a pump that is used to draw liquid fuel from the tank D and deliver said fuel to the float chamber C of the carburetor, and F designates a pressure regulator that is arranged between the pump and the float chamber of the carburetor for a purpose hereinafter described.

The pump E herein illustrated is of the diaphragm type and is provided with a flexible diaphragm G which is composed either of one or a'plurality of layers of fabric treated with a substance that will render the fabric impervious to gasolene or water, without making it brittle or inflexible, said diaphragm G being arranged so that it forms one wall of a pumping chamber 1 into which liquid fuel 'is drawn when said diaphragm flexes in one direction, and from which said liquid is forced when said diaphragm flexes in the opposite direction. My U. S. Patent No. 1,695,534, dated December 18, 1928, illustrates a a the line 22 of Figure 1, showing the float cham-v diaphragm suitable for use in the pump herein described. The diaphragm G is disk-shaped and is arranged vertically at one side of a cavity in the body portion H of the pump that constitutes the pumping chamber 1, as shown in Figure 1. 5 The peripheral edge portion of said diaphragm is clamped between an annular part on the body portion H, and a co-operating member I that serves as a support for the body portion H and also as a housing for a mechanically-operated member, hereinafter described, which forms part of the mechanism for flexing or actuating the diaphragm.

Owing to the fact that the diaphragm is constructed of fabric, it is essential that the operating mechanism for the diaphragm be of such design or construction that it will not exert thrusts. or strains on the diaphragm tending to tear or disrupt it, particularly when the float chamber of the carburetor is full and the discharge of fuel from the pumping chamber 1 is interrupted. In the form of my invention herein illustrated, the operating mechanism for the diaphragm comprises two springs 2 and '3, preferably compression springs arranged on opposite sides of the diaphragm, between the diaphragm and the parts H and I, as shown in Figure l. The spring 3, which is of greater force or strength than the spring 2, is used to impart a discharge stroke to the diaphragm, so as to create pressure in the pumping chamber 1 and expel the liquid from said chamber, and the spring 2 is used to flex the diaphragm in the opposite direction, so as to create a suction in the chamber 1 and cause the liquid to be drawn into said chamber from a source of supply. As shown in Figure 1, the spring 2 is arranged in a socket in the body portion H with one end of said spring in engagement with a member J at one side of the diaphragm, that acts as a shield to protect the diaphragm from the flushing-action of the fuel that isdrawn into the pumping chamber 1. The spring 3 is interposed between the supporting member I, and a member J that is located at the other side of the diaphragm G. Preferably, the members J and J are designed so as to embrace the central portion of the diaphragm, and they are provided at their peripheral edges with flanges which are in sliding engagement but not in snug or fuel tight contact with the body portion H and the supporting member I, respectively, of the pump housing, as shown in Figure 1. When the pump is in operation the members J and J, reciprocate back and forth, due to the pressure exerted thereon by the springs 2 and 3,

respectively, thereby causing the actuating force or pressure for the diaphragm to be centralized and applied substantially evenly to the dia- I in illustrated as consisting of a rockable member K provided with an arm 4 that co-operates with a cam or other rotatable device 5 actuated by the internal combustion engine A with which the pump is used, the pump being. of such design that the supporting member I of same can be bolted to one side of the crank case 6 of the engine, with the arm 4 of the mechanically- 'actuated element K projecting inwardly through a hole 7 in the crank case and arranged to co-operate with a cam 5, on the cam shaft 8 of the engine. As shown in Figure l, the rockable member or element K is pivotally mounted on the supporting member I, and said member is preferably forked or bifurcated so as to provide two arms that straddle or embrace a horizontally-movable cage or guide 9 on the member J which encases or houses the spring 3, said cage or guide being provided at one end with a flange 9 against which the free ends of the arms of the element K bear. When the engine is in operation, the element K rocks back and forth, and exerts pressure on the spring cage 9 in such a Way as to cause said cage to reciprocate, and thus alternately compress the spring 3 and permit said spring to expand. When the element K rocks in a direction to permit the spring 3 to expand, the pressure which said spring exerts on the diaphragm G imparts a discharge stroke to the diaphragm, or moves said diaphragm to the left, looking at Figure 1, thus causing the spring 2 to be placed under compression. Thereafter, when the element K rocks in the opposite direction, said element will compress the spring 3, and

during this period in the cycle of operations ofthe pump, the spring 2 will expand and flex the diaphragm to the right, thus causing the diaphragm to create a suction in the chamber 1 of the pump.

In" a fuel supply system of the construction above described there are times when the discharge of fuel from the pumping chamber 1 is interrupted, as, for example, when the engine is not drawing the normal quantity of fuel from the carburetor, and the inlet valve 25 of the float chamber of the carburetor is held seated by the conventional float or other means used to control said inlet valve, it being understood that the inlet valve 25 of the float chamber really acts as the control element that governs the discharge of fuel from the pumping chamber 1 of the pump. The main purpose of my invention is to permit the diaphragm to remain at rest at such times, notwithstanding the fact that the cam or other means 5 that constitutes the prime mover of the diaphragm operating mechanism continues in operation, thereby producing a fuel supply system for internal combustion engines in which the diaphragm will flex back and forth only when the carburetor is. drawing fuel from the pump, notwithstanding the fact that the engine or the prime mover 5 of the diaphragm operating mechanism operates continuously. In my improved fuel supply system the diaphragm is moved back and forth by two springs of different tension that are combined with a mechanically operated means in such a way that when the carburetor is drawing fuel from the pumping chamber 1 of the pump, one of said springs, for example, the weaker spring of the construction herein illustrated, will impart a suction stroke to the diaphragm, the stronger spring will impart a discharge stroke to the diaphragm and the mechanically-operated element 4 will alternately compress the strong spring and permit it to expand, providing, however, that the carburetor is drawing fuel from the pumping chamber, it being understood from the previous description that when the strong spring is being compressed, the weaker spring is free to expand, and thus impart a suction stroke to the diaphragm, and when the stronger spring is permitted to expand, it will overcome the force or strength of the weaker spring. If, however, the

discharge of fuel from the pumping chamber 1 is interrupted, by closing or seating of the inlet valve 25 of the float chamber of the carburetor, the diaphragm will cease operating, notwithstanding the fact that the rockable element 4 and the cam 5 continue in operation, due to the fact that the pressure then existing in the pumping chamber, plus the strength or force of the weaker spring 2, overcomes the strong spring 3 and prevents said strong spring from expanding. Hence, when the discharge of the fuel from the pumping chamber is interrupted, the pumping chamber 1 will be full of fuel, the strong spring 3 will be maintained in an inactive condition (ready to act) and the element 4 will continue to rock back and forth without having any influence or effect on the diaphragm or springs associated with same. In this way, the life of the diaphragm is materially prolonged, because it does not operate incessantly or continuously, and it is not subjected to abrupt shocks tending to strain the fabric of which the diaphragm is constructed. both of which are very important factors in a fuel feed apparatus of the kind in which a fabric diaphragm is used as the means to pump the fuel from the source of supply to the 'fuel consumption device. While I prefer to construct the diaphragm in the manner just described, I wish it to be understood that the co-acting parts or elements of said mechanism can be arranged in various other ways without departing from the spirit of my invention, as one feature of my pres- -ent invention consists of a fuel pump for carburetors provided with a fabric diaphragm, two

springs of different strength or force for moving said diaphragm back and forth, or in opposite directions, so as to alternately produce suction and pressure in the pumping chamber, a mechanically-operated device, and a part actuated by said mechanically-operated device which moves in one direction so as to compress or store up energy in the strong spring and also permit the weak spring to expand, and which moves in the opposite direction so as to permit the strong spring to expand and also compress or store up energy in the weak spring.

The pump is provided with a spring-pressed inlet valve L that opens automatically and admits the liquid to the chamber 1 of the pump during the suction stroke of the diaphragm G, and it is also provided with a discharge valve L that opens automatically and permits the liquid to escape from the said pumping chamber during the discharge stroke of the diaphragm. Any suitable type or kind of inlet and discharge valve may be used, but I prefer to use valves that are substantially flat or disk-shaped, and which act on valve seats formed by annular-shaped members 10 constructed of relatively hard, non-metallic material that has great wear resisting properties. Each valve seat is mounted upon and permanently connected to a nut or hollow metallic plug 11, which is screwed into the body member H of the pump at the lower end of the valve chamber. One convenient way of combining the non-metallic part 10 of the valve seat structure with the metallic part 11 that carries same, is to provide the part 11 with a flange 11 that is crimped or bent over the peripheral edge of the annular valve seat member 10, as shown in Figure 3. In order to facilitate screwing the member 11 into and out of the threaded opening provided for same in the body portion of the pump, said member 11 is provided on its interior with a hole 12 of non-circular shape into which a non-circular-shaped member can be introduced.

The pump E can either be equipped with an inlet pipe that leads directly to the inlet valve. or it can be equipped with a bowl or reservoir to which the liquid is admitted by a supply pipe and from which the liquid thereafter escapes into the'chamber 1 of the pump through the passageway controlled by the inlet valve. In the form of my invention herein illustrated the pump is provided with a bowl M detachably connected to the body portion H of the pump and arranged so that the interior of same communicates with the inlet passageway in said body portion, in which the inlet valve L is arranged. Liquid is supplied to the bowl M by a supply pipe 13 attached to the body portion H of the pump and arranged so as to discharge downwardly into the upper end of the bowl M, as shown in Figure 1. In order to prevent foreign matter from being carried into the chamber 1 of the pump with the liquid, a screen 14 is arranged at the upper end of the bowl M in such a position that the liquid will have to pass upwardly through said screen in traveling to the inlet valve. Any suitable means can be used to retain the bowl M in position, the means herein illustrated consisting of a bail 15 pivotally connected to the body portion H of the pump and arranged so that the cross piece of said bail will bear against a part connected to the bowl, and thus exert sumcient upward pressure on the bowl. The bowl M is preferably provided with a depending, extemally-screw-threaded part 16 on which a nut 1'7 is adjustably mounted, said nut being provided on its underside with a concaved recess that is adapted to receive a convexed projection 18 on the cross piece of the bail 15. By adjusting the nut 17 upwardly or downwardly, the upward pressure which the bail 15 exerts on the bowl M can be varied; thereby making it possible to maintain a tight joint between the top edge of the bowl M and the part against which it bears. The discharge pipe 19 of the pump leads from the chamber of the discharge valve L to the float chamber C of the carburetor B.

The diaphragm G is combined with the body portion H and with the supporting member I in such a way as to produce a slight buckle in the diaphragm, which insures a quick movement or sudden movement of the diaphragm each time it reverses or changes its direction of movement. In the pump herein illustrated the buckle in the diaphragm is produced by forcing the peripheral portion of the diaphragm into a circular recess, of slightly less diameter than the diaphragm, formed in one of the parts between which the peripheral edge portion of the diaphragm is clamped. Thus, as shown in Figure 1, the portion of the supporting member I that is arranged in opposed relation to the annular part on the body portion H that bears against the peripheral 901'- tion of the diaphragm, is provided with a circular recess, designated by the reference character 21, of substantially the same depth as the thickness of the diaphragm, but of slightly less diameter than the diaphragm. In assembling the diaphragm with the parts with which it co-operates, the peripheral edge portion of the diaphragm is forced into the recess 21 in the supporting member I, thus causing the diaphragm to buckle slightly, and thereafter, said supporting member is connected with the body portion H by means of screws or other suitable fastening devices 22 that pass through the said supporting member I and through a flange 20 on the body portion H at a point beyond the peripheral edge of the diaphragm, as shown in Figure 1.

As previously stated, the peripheral portion of the diaphragm G is clamped between opposed parts on the members H and I, and the central portion of the diaphragm is embraced by the members J and J The members J and J which embrace the central portion of the diaphragm are so proportioned and arranged with relation to the members H and I which grip the peripheral portion of the diaphragm that there is an annular portion of the diaphragm lying between these two points which is free to flex back and forth, and thus alternately create suction and pressure in the pumping chamber 1, when the pump is in operation, said intermediate portion assuming substantially the shape of two reverse curves in either of the extreme positions of the diaphragm. In order to prevent this intermediate, flexible portion of the diaphragm from being subjected to strains tending to disrupt or tear it, when the diaphragm makes a full stroke in either direction, I have provided the shield member J with a convexed annular surface 23 that co-operates with a reversely curved, convexed'surface 24 on the member I to form a supporting surface for substantially the entire area of the flexible intermediate portion of the diaphragm when said diaphragm is at the end of its suction stroke, as shown in Figure 4, and I have provided the member J with a convexed annular surface 23a that co-operates with a reversely curved, convexed surface 245a on the member H to form a supporting surface for substantially the entire area of the flexible intermediate portion of the diaphragm when said diaphragm is at the end of its discharge stroke, as shown in Figure 5. The curvature of the supporting surfaces just referred to may be varied, but it is preferable to proportion or design said surfaces, so that each surface has a drop equal to one-fourth of the stroke of the diaphragm, and have the oppositely-curved surfaces 23 and 23a on the members J and J, respectively, located in such relationship with the oppositelycurved surfaces 24 and 24a on the members I and H, respectively, that substantially the entire area of the flexible portion of the diaphragm will be backed up and efiectively supported when the diaphragm is in either of its extremely flexed positions. Consequently, notwithstanding the fact that the diaphragm is formed of fabric, it has a long life and will remain in an operative condition for along period of time, because the flexible intermediate portion of same is not subjected to strains or pressures tending to disrupt it or tear it away either from the members that grip the peripheral portion of the diaphragm, or the members which clamp or bear against the opposite sides of the central portion of the diaphragm.

The features just described form the subjectmatter of my pending application for Patent Serial No. 657,357, filed February 18, 1933.

I have herein illustrated the pump as being equipped with a pressure regulator F which may or may not be used as it forms no part of my present invention. Said pressure regulator F comprises a governing member 26 which is so constructed and arranged that a relatively slight pressure in the discharge pipe 19 of the pump will be exerted on the governing member 26 and cause said member to hold the dischargevalve L' of the pump seated, even though the pressure in the pumping chamber 1 is far in excess of the pressure in the discharge pipe 19. The area of the governing member 26 that is exposed to the pressure in the discharge pipe 19 is far in excess of the area of the discharge valve L that is exposed to the pressure in the pumping chamber 1, and isso proportioned that said discharge valve will remain seated so long as the needle valve or inlet valve 25-of the float chamber C remains seated, but will open on the discharge stroke of the diaphragm, providing the inlet valve of the float chamber has opened, due to a drop in the level of the fuel in the float chamber, thereby permitting a charge of fuel to pass from the pumping chamber 1 into the discharge pipe 19, the discharge valve L closing automatically as soon as the former pressure ratio has been reestablished. The governing member 26 of the pressure regulator F herein illustrated consists of a flexible diaphragm that forms one wall of a chamber 27, which is in direct communication with the discharge pipe 19 of the pump, the chamber 27 being formed in a housing 28 mounted on the body portion H of the pump, and provided with a duct 29 that leads from the chamber 27 to the discharge pipe 19, as shown in Figure 2. Various means can be used for causing the governing member 27 to exert pressure on the discharge valve L in a direction to hold said valve seated, the means herein illustrated consisting of a plunger 30 sustained by a spring 31 and arranged above the discharge valve L' in alignment with a stem 32 on the top side of said valve, a pair of pivotally mounted levers 33 in the chamber 27 whose inner ends bear downwardly on the upper end of the plunger 30, and a cross piece 34 attached to the center of the governing member 26 on the underside of same and provided at its ends with hooks or yokes 3411 that receive the outer ends of the levers 33. When the governing member 26 flexes upwardly, due to the pressure exerted on the underside of the same, the inner ends of the levers 33 swing downwardly, thereby exerting pressure on the discharge valve L in a direction to hold it seated, a diminution in the pressure in the discharge pipe 19 produced by unseating of the inlet valve of the float chamber C permitting the governing member 26 to flex downwardly slightly, thus relieving the pressure on'the stem of the discharge valve and permitting said-valve to open during the discharge stroke of the diaphragm G of the pump. The

housing 28 which the chamber is formedispreferably provided with a removable cap piece or cover 35 that protects the governing element 26 of the pressure regulator, said cap piece having an air vent 35a.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

. chamber that controls the discharge. of fuel from the said pumping chamber, two springs of different strength or force arranged at opposite sides of the diaphragm for moving the diaphragm back and forth, and a constantly operating engine driven means that moves first in one direction to store up energy in said stronger spring and then moves in the opposite direction to permit said stronger spring to expand and simultaneously compress the weaker spring, thereby imparting a discharge stroke to the diaphragm, said springs being of such tension that when the discharge of fuel from the pumping chamber is momentarily interrupted in the normal functioning of the carburetor said diaphragm will remain at rest, notwithstanding the fact that said constantly operating engine driven means continues in operation.

2. A pump for supplying fuel to an internal combustion engine, comprising two casing members provided with co-acting annular-shaped parts, a flexible non-metallic diaphragm clamped between said annular-shaped parts and arranged to form one wall of a pumping chamber produced by a cavity in one of said casing members, a bore in said last-mentioned casing member, a spring in said bore arranged at one side of the diaphragm, a spring in the other casing member arranged at the opposite side of the diaphragm, said springs being of different strength or force, and a constantly operating engine driven means that moves in one direction to store up energy in the stronger spring and then moves in the opposite direction to permit the stronger spring to expand and simultaneously compress the weaker spring, thereby imparting a discharge stroke to the diaphragm, said springs being of such tension that if the discharge of fuel from the pumping chamber is momentarily interrupted in the normal functioning of the apparatus to which the pump is supplying fuel, the diaphragm will remain at rest notwithstanding the fact that the constantly operating engine driven means con- 1 tinues in operation.

WILLIAM C. CARTER. 

